A sand transportation barge sits in the water near the St. Francis Yacht Club after being intentionally run aground in San Francisco on Tuesday. The barge began taking on water and was run aground to prevent it from sinking in deeper waters.

Photo: Laura Morton, Special To The Chronicle

A sand transportation barge sits in the water near the St. Francis...

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Workers put oil containment booms around a barge that ran aground in the water near the St. Francis Yacht Club in San Francisco on Tuesday. The sand transportation barge was intentionally run aground after it began taking on water and booms were put out as a precautionary measure.

Photo: Laura Morton, Special To The Chronicle

Workers put oil containment booms around a barge that ran aground...

Image 3 of 6

A worker from NRC Environmental Services helps tie down an oil containment boom around a barge that ran aground in the water near the St. Francis Yacht Club in San Francisco on Tuesday. The sand transportation barge was intentionally run aground after it began taking on water and booms were put out as a precautionary measure.

Photo: Laura Morton, Special To The Chronicle

A worker from NRC Environmental Services helps tie down an oil...

Image 4 of 6

A sand transportation barge sits in the water near the St. Francis Yacht Club after being intentionally run aground in San Francisco on Tuesday. The barge began taking on water and was purposefully run aground to prevent it from sinking in deeper waters.

Photo: Laura Morton, Special To The Chronicle

A sand transportation barge sits in the water near the St. Francis...

Image 5 of 6

Workers put oil containment booms around a barge that ran aground in the water near the St. Francis Yacht Club in San Francisco on Tuesday. The sand transportation barge was intentionally run aground after it began taking on water and booms were put out as a precautionary measure.

Photo: Laura Morton, Special To The Chronicle

Workers put oil containment booms around a barge that ran aground...

Image 6 of 6

Workers set up oil containment booms as a precautionary measure on a barge that was intentionally run aground near the St. Francis Yacht Club in San Francisco, Calif., on Tuesday, February 15, 2011. The barge began taking in water and was purposefully run aground to prevent it from sinking in deeper waters.

Fuel and hydraulic fluid leaked from a sinking barge Tuesday near the St. Francis Yacht Club, prompting an emergency cleanup operation.

The barge, which was carrying sand from a dredging operation, was intentionally run aground at about 7:30 a.m. Tuesday after it began taking on water, said Levi Read, a spokesman for the U.S. Coast Guard. An oily substance was then spotted in the bay, but authorities do not believe it was the result of a fuel-tank rupture.

"We have no huge amount of fuel product going into the environment," said Lt. Brian Arnold of California Fish and Game.

The incident began when the Coast Guard gave the captain of a tugboat permission to ground the barge on San Francisco's shoreline so it would not sink, said Robert Gregory, regional operations manager for Foss Maritime Co., the owner of the vessel.

Seeing that an unknown amount of petroleum product had already leaked out of the boat and into the water, the Coast Guard and a private oil-spill-response company began surrounding the barge with booms designed to prevent the spread of oil.

The barge carries 4,800 gallons of fuel and 500 gallons of hydraulic fluid, authorities said. It is unclear how much of either substance leaked into the bay, but an aerial search identified only two small patches of sheen on the water. By Tuesday afternoon, the barge was no longer leaking fuel, authorities said.

Salvage crews now will begin the process of removing 3,000 tons of sand from the barge so the cause of the leak can be investigated and the remaining fuel can be pumped out of the ship, Gregory said. The vessel was double-wrapped with boom material Tuesday in preparation for an overnight storm that forecasters predicted would pound the Bay Area.